1. Field of the Invention
The present invention relates to a projection type video display apparatus such as a liquid crystal projector.
2. Description of the Background Art
[1] An example of a projection type video display apparatus is one comprising distance detection means for detecting the distance between a person who exists within a projected video area (within an optical path of projected light) and the projection type video display apparatus to prevent the person from feeling dazzling by adjusting the amount of projected light when the distance detection means detects that the person exists in the vicinity of the projection type video display apparatus. The distance detection means is composed of a light receiving element (an optical sensor), to presume the distance between the person and the projection type video display apparatus by the amount of light reflected from the person that has been received by the light receiving element (see JP-A-6-347748).
In the projected video area, however, even when the person is at a position spaced apart from the projection type video display apparatus, the person feels dazzling when he or she looks toward the projection type video display apparatus. In a conventional configuration in which the amount of projected light is adjusted only when the person exists in the vicinity of the projection type video display apparatus, the person feels uncomfortable by the projected light.
The distance between the projection type video display apparatus and a screen differs depending on the disposition of a room in which the projection type video display apparatus is employed. When the distance between the projection type video display apparatus and the screen becomes extremely short, the amount of the light received in the light receiving element may, in some cases, be increased even when no person exists within the projected video area. As a result, it is erroneously detected that the person exists in the vicinity of the projection type video display apparatus irrespective of the fact that no person exists within the projected video area, so that the amount of the projected light is adjusted. Therefore, a person who is watching a video feels uncomfortable by a sudden change in the amount of the projected light.
An object of the present invention is to provide a projection type video display apparatus capable of making it possible to prevent a person who exists within a projected video area from feeling uncomfortable as well as to also prevent a person who is watching a video from feeling uncomfortable.
[2] Known as a projection type video display apparatus is one comprising a CCD camera for imaging a projected video area, character position detection means for detecting position information relating to a person who exists within the projected video area from imaging information obtained by the CCD camera, and video light luminance adjustment means for determining a luminance adjustment area on the basis of the position information from the character position detection means, and so adapted that in a case where the person exists within the projected video area, its state is detected by the imaging information from the CCD camera, and the luminance of video light is adjusted only with respect to the area where the person exists to prevent the person who exists within the projected video area from feeling dazzling (see JP-A-2000-305481).
However, the imaging information obtained by the CCD camera includes not only information relating to a person who stands in front of a screen of the projection type video display apparatus to make a presentation but also information relating to a person who is projected as a character on a video because the person appears in a film or the like. As a result, every time the person who appears in the film is projected as the character on the video, the luminance of video light around the character is changed irrespective of the fact that no person exists in front of the projection type video display apparatus, so that a person who is watching the film feels uncomfortable.
Considered in order to solve this problem is a configuration in which there is provided person detection means for detecting the heat of a person to detect the existence of the person. Although in this configuration, the existence of the person can be detected, however, the position where the person exists cannot be detected. Not only an area where the person exists but also the luminance of the whole of a video is changed, so that a person who is watching a film or the like feels uncomfortable.
An object of the present invention is to provide a projection type video display apparatus capable of reliably detecting a person who exists within a projected video area of a projection type video display apparatus as well as detecting the position of the person who exists within the projected video area, and capable of preventing the person who exists within the projected video area and a person who is watching a video from the projection type video display apparatus from feeling uncomfortable.